This invention relates to novel anti-allergic agents which are optionally substituted 4-hydroxy[1]benzothieno[3,2-f]-quinoline-2-carboxylic acids and salts thereof, to novel intermediates useful for the synthesis of said anti-allergic agents, to processes for the synthesis of said anti-allergic agents and to methods for the use of these novel anti-allergic agents.
The basic ring structure of the compounds of the present invention is novel. The closest known ring structures having the ring sequence C.sub.4 S,C.sub.5 N,C.sub.6,C.sub.6 are believed to be [1]-benzothieno[2,3-b]quinoline, [1]benzothieno[3,2-b]quinoline, thieno[3,2-c]acridine, thieno[3,4-c]acridine and thieno[2,3-c]-acridine as reported in "The Ring Index", Reinhold Publishing Company, 1940.